A DEFINED SYSTEM FOR IN-VITRO LAMBDA-DNA PACKAGING

We constructed a defined in vitro system for packaging lambda DNA which is composed of purified proheads, the noncapsid proteins terminase and gpFl, and the Escherichia coli DNA binding/bending protein IHF. The defined packaging system: (i) is free from endogenous ATP, DNAs, and DNases and (ii) packages 30% of the input mature lambda DNA efficiently. In this defined packaging system, IHF and gpFl make modest contributions to packaging efficiency. The defined packaging reactions showed that DNA packaging gave a linear response to the concentration of mature lambda DNA and terminase. DNA packaging showed a sigmoidal relationship with respect to the concentration of ATP and proheads. (C) 1995 Academic Press, Inc.